#ifndef CLASS_STUDY_H_
#define CLASS_STUDY_H_
class Animal
{
protected:
    int height;

public:
    Animal(int height);
    virtual ~Animal() =0;
    virtual void eat() =0 ;
};

class Bird : public Animal
{
private:
    /* data */
public:
    Bird(int height);
    ~Bird();
    void eat() override;
    void fly();
};

#endif